// FIXME 缺少 set 函数

const mimeMap = require('./mimeMap.js')

function FormData() {
  let fileManager = wx.getFileSystemManager()
  let data = {}
  let files = []

  this.append = (name, value) => {
    data[name] = value
    return true
  }

  this.appendFile = (name, path, fileName = null) => {
    let buffer = fileManager.readFileSync(path)
    if (Object.prototype.toString.call(buffer).indexOf('ArrayBuffer') < 0) {
      return false
    }
    files.push({
      name: name,
      buffer: buffer,
      fileName: fileName || getFileNameFromPath(path)
    })
    return true
  }

  this.setFile = (name, path, fileName = null) => {
    let buffer = fileManager.readFileSync(path)
    if (Object.prototype.toString.call(buffer).indexOf('ArrayBuffer') < 0) {
      return false
    }
    let file = files.find(file => file.name === name)
    if (file) {
      file.buffer = buffer
      file.fileName = fileName || getFileNameFromPath(path)
    } else {
      files.push({
        name: name,
        buffer: buffer,
        fileName: fileName || getFileNameFromPath(path)
      })
    }
    return true
  }

  this.delete = (name) => {
    delete data[name]
    return true
  }

  this.deleteFile = (name) => {
    let index = files.findIndex(item => item.name === name)
    if (index < 0) {
      return false
    }
    files.splice(index, 1)
    return true
  }

  this.get = (name) => {
    return data[name]
  }

  this.getData = () => convert(data, files)
}

function getFileNameFromPath(path) {
  let idx = path.lastIndexOf('/')
  return path.substr(idx + 1)
}

function convert(data, files) {
  let boundaryKey = 'wxmpFormBoundary' + randString() // 数据分割符，一般是随机的字符串
  let boundary = '--' + boundaryKey
  let endBoundary = boundary + '--'

  let postArray = []
  //拼接参数
  if (data && Object.prototype.toString.call(data) == '[object Object]') {
    for (let key in data) {
      postArray = postArray.concat(formDataArray(boundary, key, data[key]))
    }
  }
  //拼接文件
  if (files && Object.prototype.toString.call(files) == '[object Array]') {
    for (let i in files) {
      let file = files[i]
      postArray = postArray.concat(
        formDataArray(boundary, file.name, file.buffer, file.fileName)
      )
    }
  }
  //结尾
  let endBoundaryArray = []
  endBoundaryArray.push(...endBoundary.toUtf8Bytes())
  postArray = postArray.concat(endBoundaryArray)
  return {
    contentType: 'multipart/form-data; boundary=' + boundaryKey,
    buffer: new Uint8Array(postArray).buffer
  }
}

function randString() {
  let res = ''
  for (let i = 0; i < 17; i++) {
    let n = parseInt(Math.random() * 62)
    if (n <= 9) {
      res += n
    } else if (n <= 35) {
      res += String.fromCharCode(n + 55)
    } else {
      res += String.fromCharCode(n + 61)
    }
  }
  return res
}

function formDataArray(boundary, name, value, fileName) {
  let dataString = ''
  let isFile = !!fileName

  dataString += boundary + '\r\n'
  dataString += 'Content-Disposition: form-data; name="' + name + '"'
  if (isFile) {
    dataString += '; filename="' + fileName + '"' + '\r\n'
    dataString += 'Content-Type: ' + getFileMime(fileName) + '\r\n\r\n'
  } else {
    dataString += '\r\n\r\n'
    dataString += value
  }

  var dataArray = []
  dataArray.push(...dataString.toUtf8Bytes())

  if (isFile) {
    let fileArray = new Uint8Array(value)
    dataArray = dataArray.concat(Array.prototype.slice.call(fileArray))
  }
  dataArray.push(...'\r'.toUtf8Bytes())
  dataArray.push(...'\n'.toUtf8Bytes())

  return dataArray
}

function getFileMime(fileName) {
  let idx = fileName.lastIndexOf('.')
  let mime = mimeMap[fileName.substr(idx)]
  return mime ? mime : 'application/octet-stream'
}

String.prototype.toUtf8Bytes = function () {
  var str = this
  var bytes = []
  for (var i = 0; i < str.length; i++) {
    bytes.push(...str.utf8CodeAt(i))
    if (str.codePointAt(i) > 0xffff) {
      i++
    }
  }
  return bytes
}

String.prototype.utf8CodeAt = function (i) {
  var str = this
  var out = [],
    p = 0
  var c = str.charCodeAt(i)
  if (c < 128) {
    out[p++] = c
  } else if (c < 2048) {
    out[p++] = (c >> 6) | 192
    out[p++] = (c & 63) | 128
  } else if (
    (c & 0xfc00) == 0xd800 &&
    i + 1 < str.length &&
    (str.charCodeAt(i + 1) & 0xfc00) == 0xdc00
  ) {
    // Surrogate Pair
    c = 0x10000 + ((c & 0x03ff) << 10) + (str.charCodeAt(++i) & 0x03ff)
    out[p++] = (c >> 18) | 240
    out[p++] = ((c >> 12) & 63) | 128
    out[p++] = ((c >> 6) & 63) | 128
    out[p++] = (c & 63) | 128
  } else {
    out[p++] = (c >> 12) | 224
    out[p++] = ((c >> 6) & 63) | 128
    out[p++] = (c & 63) | 128
  }
  return out
}

module.exports = FormData
